1. Field of the Invention
Embodiments of the present invention relate to a fan ramp of a pivot door thrust reverser. More particularly, embodiments of the present invention relate to a fan ramp with a variable shape at the aft end.
2. Description of the Related Art
Airplane engines on business or regional jets often include pivot door type thrust reversers. Generally, there are two pivot doors at the aft portion of the engine—one that opens (or pivots) in the up direction and one that opens in the down direction. The engine also includes a fan ramp that guides airflow past the turbine when reverse thrust is not needed and the pivot doors are stowed. When reverse thrust is needed, the pivot doors are deployed and the fan ramp helps to guide airflow in the reverse direction.
Ideally, during reverse thrust, air should flow through the fan ramp and split evenly as it encounters the pivot doors. Half the airflow should go in the up direction and be guided back to the forward part of the engine and the other half of the airflow should go in the down direction and be guided back to the forward part of the engine. Typically, the fan ramp has a curved or flared portion that is uniform around the circumference of the aft section. This uniform trailing edge of the fan ramp may allow some of the airflow to go in either the left or right direction, avoiding the deployed pivot doors and not getting redirected back to the forward part of the engine—a condition know as side spillage. As a result, the ability of the engine to efficiently redirect airflow is diminished and reverse thrust is reduced.